Carton



July 13, 1965 w, c, RALSTON 3,194,475

CARTON Filed June 11, 1964 INVENTOR.

WILLIAM C. RALSTON BY ATTOZEY i United States Patent 0 3,194,475 Patented July 13, 1955 3,194,475 CARTON William C. Ralston, Owenshoro, Ky., assignor to General Electric Company, a corporation of New York Filed June 11, 1964, Ser. No. 374,407

3 Claims. (Cl. 229-38) This invention. relates to a carton for enclosing fragile articles and, more particularly, to a new and improved locking flap for such cartons.

Heretofore cartons and boxes have been fabricated from cardboard or similar material generally to have two interior flaps and an exterior cover flap which may be moved from closed to open positions to conceal or reveal the interior compartment. Each flap usually consists ofan extended portion of one sidewall foldable at a right angle thereto. A locking flap extends from one edge of the exterior cover flap and is folded therealong to enable insertion into a slotfor securing the cover in the closed position. The slot is usually defined by edges of the interior flaps and the face of one sidewall. To insure engagement of the locking flap in the slot, the locking flap has been partially severed from the exterior cover flap by inwardly extending slits at both ends of the fold therebetween. The resulting edge discontinuity formed by the slits operates to provide snug engagement of the locking flap in the corners of the slot and to retard accidental release or opening.

In cartons for enclosing electronic tubes or the like, it is imperative, due to the fragility of the contents, that the cover locking means be reliable and not likely to fail or accidentally to disengage. Electronic servicemen and others handling such cartons are accustomed to frequently open and close tube cartons in order to substitute various tubes in electronic equipment when spot checking for faulty tubes or for other purposes. The carton locking means heretofore provided and as described above tends to fail after limited repeated use because the slits between the exterior cover flap and the locking flap tend to become elongated and the locking flap eventually becomes severed from the exterior cover flap. As a result, the carton is rendered incapable of properly protecting its fragile contents because of the loss of the locking feature.

The present invention overcomes this problem which has accompanied cartons heretofore provides and achieves a locking arrangement which sustains repeated use without diminishing the locking feature.

It is therefore an object of this invention to provide an improved carton with a novel locking flap for such carton.

Another object of this invention is to provide a carton having a novel cover construction which insures firm engagement of the locking flap and allows repeated use without destroying the locking function.

A further object of this invention is to provide a new and improved carton having a locking flap for the cover thereof which enables repeated use without causing severance of the locking flap from the cover.

In carrying out this invention in one form thereof, my novel carton comprises a locking flap which extends from an exterior cover flap and is employed for engagement in a slot defined by one carton sidewall and the edges of interior flaps folded beneath the exterior cover. The locking flap is folded along one edge of the folded exterior cover flap adjacent the slot into which the locking flap is adapted to be inserted. Curvilinear indentations are provided along the edges of the locking flap adjacent the fold. Curvilinear shoulders are provided along the edges adjacent the indentations. The shoulders operate to engage the corners of the slot during the initial phase of withdrawal of the locking flap from the slot, thereby retarding such withdrawal. Due to the curvilinear nature of the shoulders and the absence of slits or sharp notches, there is no severance between the locking flap and cover encountered with arrangements heretofore described. Also, when the locking flap is fully inserted into the slot, the curvilinear indentations relieve stresses between the slot and the locking flap and thereby reduce wear.

For a better understanding of the invention, reference is made to the accompanying drawings in which:

FIGURE 1 illustrates an unfolded blank of the carton of my invention;

FIGURE 2 is top view partly in section of a carton with the exterior cover flap and locking flap in an unfolded condition;

FIGURE 3 is a fragmentary perspective view of a carton with the locking flap partially inserted and in unlocked condition in the locking slot;

FIGURE 4 is a similar perspective view with the locking flap fully inserted and locked in the locking slot.

Referring now to FIGURE 1, a carton constructed in accordance with my invention is shown as an unfolded blank of chip board, card board or other suitable material and having four sidewalls 1, 2, 3, and 4 with score lines 18 therebetween to enable folding of the blank to form an enclosure of parallelepiped configuration. Interior cover flaps 6 and 7 extend from and are joined to each end of sidewalls 1 and 2 by score lines 17, and exterior cover flaps 5 extend from and are joined to one end of each of the sidewalls 3 and 4 by score lines 16, the exterior cover flaps 5 being provided at the opposed ends of walls 3 and i.

In FIGURE 2, a carton is indicated in a top view showing the edges of the four carton sidewalls 1, 2, 3, and 4. A pair of interior flaps 6 and 7 are folded inwardly to overlap at the carton opening. An exterior cover flap 5 is capable of being folded over the interior flaps 6 and 7. A locking or tuck-in flap 8 is formed as an extension of the exterior cover flap 5 and is adapted to be folded relative to the exterior cover flap 5 along a score line 9.

A slot or opening 12 is defined at the top of the carton by the interior surface of the sidewall 3 and the angled edges 15 of the interior flaps 6 and 7. The slot 12 has a narrow corner 13, at each end of the sidewall 3, formed by the angled edges 15 of the interior flaps 6 and 7. The exterior cover flap 5 is capable of being locked in a closed position by inserting the locking flap 3 into the slot 12.

The locking flap 8 and the exterior cover flap 5 define a continuous edge 14 along which a pair of curvilinear indentations 10 are disposed generally at the ends of the score line 9. For maximum positive locking the deepest parts of the indentation are preferably offset from the score line'9 toward the cover flap 5 byan amount equal to the thickness of the board stock of which the carton is made. A pair of curvilinear shoulders 11 are formed by the edges of the locking flap 8 adjacent the curvilinear indentations 19. The width of the locking flap between the curvilinear shoulders 11 is substantially equal to the distance between the sidewalls 1 and 2. 7

After the exterior cover flap Shas been folded over the interior flaps 6 and 7, it may be held in this closed position by inserting the locking flap 8 into the slot 12 as indicated in FIGURE 3. To insert the locking flap 3 into the slot 12, it is necessary to force the shoulders 11 of the locking flap 3 past the narrow corners 13 of the slot 12, since the width of the locking flap 8 between the shoulders 11 is slightly greater than the width of the slot due to the narrow corners 13. After the locking flap 8 has been fully inserted into the slot 12, as shown in FIG- URE 4, the exterior cover flap 5 is maintained adjacent the folded interior flaps 6 and 7 as shown in FIGURE 4. The exterior cover flap 5 is locked in this position since withdrawal of the locking flap 8 from the slot 12 is retarded by the attendant resistance between the shoulders 11 and the narrow corners 13. While the locking flap is maintained fully inserted into the slot 12, the curvilinear indentations are positioned adjacent the narrow corners 13 and the curvilinear shoulders 11 are maintained out of engagement therewith, By positioning the curvilinear indentations adjacent the narrow corners, the corners are thereby relieved of any distorting force thereby measurably increasing the useful life of this feature of the carton.

By employing curvilinear indentations and shoulders along a continuous edge formed by an exterior cover flap and a locking flap, an improved locking engagement is obtained whereby severance of the locking flap is prevented by the curvilinear contour, and Wear is reduced by the indentations which relieve distortion between the locking flap and the slot.

The bottom end of the carton of my invention is formed in a manner and with means similar to those just described. Hence a full description of the bottom end is deemed to be unnecessary.

To facilitate opening of the top and/ or bottom flaps,

indentations, as at 19, may be formed in the free ends of the sidewalls 3 and 4.

While a specific embodiment of this invention has been shown and described, it is not desired that the invention be limited to the, particular construction shown and described and it is intended by the appended claims to cover all modifications within the spirit and scope of this invention.

WhatI claim as new and desire to secure by Letters Patent of the United States is:

1. A carton having a plurality of sidewalls defining an enclosure and an opening at the end of said enclosure.

(a) a pair of fold-able interior flaps extending from a first and a second sidewall for folding over said 'opening, the interior surface-of a third sidewall and edges of said interior flaps adjacent said third sidewall defining a slot, said edges of said third side-wall being cut at an angle to provide converging corners for said slot,

(-b) an exterior cover flap extending from a ;fourth sidewall toldable to cover said interior flaps,

(c) a locking flap extending from said exterior cover (d) said exterior cover fiap and said locking flap having a continuous edge with at least one curvilinear edge portion along said continuous edge at the junction of said exterior cover flap and said lockingflap, (e) at least one curvilinear shoulder along said continuous edge on said locking flap adjacent said curvilinear portion for securing said locking flap inv said slot.

(f) said locking flap being folded at an angle to said cover flap and inserted in said slot,whereby said curvilinear edge portion provides clearance between said cover flap and said corners of said slot and said curvilinear shoulder engages said corner of said slot to retard withdrawal of the locking flap from said slot.

'2. In a carton having four sidewalls and an opening at the end of said sidewalls,

(a) a pair of folded interior flaps extending-from a first and asecond sidewall'for folding over said opening,

(b) a slot defined by the interior surface of a third & sidewall and edges of said interior flaps, said slot having a pair of converging corners, Y

(c) an exterior cover flap extending from a third sidewall and a locking flap extending from said exterior cover flap,

(d) a score linev between said exterior cover flap and said locking flap, V I

(e) said exterior cover flap and said locking flap having acontinuous edge with a curvilinear indentation along said edge at each end of the score line between said locking :fiap and said exterior cover flap,

(f) a curvilinear shoulder along said continuous'edge of said locking flap adjacent each of said curvilinear indentations, i

(g) said 'locking flap being folded at the score line and inserted into said slot whereby said curvilinear indentations provide clearance between said cover ilap and said corners of said slot and said curvilinear shoulders retard withdrawal of the locking flap from said slot.

3. In a carton having four sidewalls and an opening at the end of said sidewalls,

(a) a pair of folded interior flaps extending from a first and a second sidewall for folding over said opening,

(b) a slot defined by the interior surface of a third sidewall and edges of said interior flaps, said edges of said'interior flaps being cut at an angle to said third sidewall to form converging corners for said 7 slot,

(c) an exterior cover fiap extending from the end of a fourth sidewall and a locking flap formed by a 'folded extension of said exterior cover flap, said locking flap having a width substantially equal to the distance between said first and said second sidewalls,

(d) said exterior cover flap and said locking flap having a continuous edge with curvilinear indentations along said edge at each end of the fold between said exterior cover flap and said locking flap,

(e) a curvilinear shoulder along said continuous edge of said locking fiap adjacent each of said curvilinear indentations, the distance between said shoulders being substantially equal to the distance between said first and said second sidewalls, and

( f) said locking flap being inserted in said slot, whereby said shoulders on said *locking flap engage the corners of said slot to retard withdrawal of said locking flap and said curvilinear indentations provide clearance between said continuous edge and said converging corners of said slot.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 4/28" Great Britain.

JOSEPH R. LECLAIR,-Primary Examiner.

FRANKLINT. GARRETT, Examiner, 

1. A CARTON HAVING A PLURALITY OF SIDEWALLS DEFINING AN ENCLOSURE AND AN OPENING AT THE END OF SAID ENCLOSURE. (A) A PAIR OF FOLDABLE INTERIOR FLAPS EXTENDING FROM A FIRST AND A SECOND SIDEWALL FOR FOLDING OVER SAID OPENING, THE INTERIOR SURFACE OF A THIRD SIDEWALL AND EDGES OF SAID INTERIOR FLAPS ADJACENT SAID THIRD SIDEWALL DEFINING A SLOT, SAID EDGES OF SAID THIRD SIDEWALL BEING CUT AT AN ANGLE TO PROVIDE CONVERGING CORNERS FOR SAID SLOT, (B) AN EXTERIOR COVER FLAP EXTENDING FROM A FOURTH SIDEWALL FOLDABLE TO COVER SAID INTERIOR FLAPS, (C) A LOCKING FLAP EXTENDING FROM SAID EXTERIOR COVER FLAP, (D) SAID EXTERIOR COVER FLAP AND SAID LOCKING FLAP HAVING A CONTINUOUS EDGE WITH AT LEAST ONE CURVILINEAR EDGE PORTION ALONG SAID CONTINUOUS EDGE AT THE JUNCTION OF SAID EXTERIOR COVER FLAP AND SAID LOCKING FLAP, (E) AT LEAST ONE CURVILINEAR SHOULDER ALONG SAID CONTINUOUS EDGE ON SAID LOCKING FLAP ADJACENT SAID CURVILINEAR PORTION FOR SECURING SAID LOCKING FLAP IN SAID SLOT. (F) SAID LOCKING FLAP BEING FOLDED AT AN ANGLE TO SAID COVER FLAP AND INSERTED IN SAID SLOT, WHEREBY SAID CURVILINEAR EDGE PORTION PROVIDES CLEARANCE BETWEEN SAID COVER FLAP AND SAID CORNERS OF SAID SLOT AND SAID CURVILINEAR SHOULDER ENGAGES SAID CORNER OF SAID SLOT TO RETARD WITHDRAWAL OF THE LOCKING FLAP FROM SAID SLOT. 